What is the number one weapon in fighting childhood poverty in the United States? Marriage.

Put another way, the disappearance of marriage in low-income communities is the predominant cause of poverty for children today. If poor single mothers were married to the actual fathers of their children, two- thirds would immediately escape from poverty. What's more, the absence of husbands and fathers from the home is a strong contributing factor to crime, failure in school, drug abuse, emotional disturbance and a host of other social problems.

In Michigan, only 5.9 percent of children in families headed by a married couple are poor. But the poverty rate of children of single mothers is 39.7 percent. Marriage drops the odds of poverty by 85 percent.

True, married couples in general are better educated than single moms. However, the dramatic impact of marriage in reducing poverty is largely unchanged even after adjusting for differences in education and race.

The collapse of marriage also lies at the heart of the mushrooming welfare state.

This year taxpayers will spend over $300 billion providing means-tested welfare aid to single parents. The average single mother receives nearly three dollars in government benefits for each one dollar in taxes paid.

Who pays for these subsidies? Higher-income married couples, through heavy taxes.

When President Lyndon B. Johnson launched the War on Poverty in 1964, only 7 percent of births in America were outside marriage. Today more than 40 percent are.

A staffer in the Johnson White House, Daniel Patrick Moynihan, warned the nation of the calamities associated with the growing rate of out-of-wedlock births. For more than 40 years, Moynihan's warnings have largley been ignored. The result? A social and economic disaster.

Now, in inner-cities like Detroit, births outside marriage often top 80 percent.

Why has marriage all but disappeared in many low-income communities? Part of the answer is welfare. Bureaucrats largely designed the welfare system to serve as a substitute for a husband in the home. Most welfare programs actually penalize low-income couples for marrying.

A second reason for the collapse of marriage: Norms have changed in lower-income groups. Women who have children outside marriage strongly desire children - non-marital births are seldom the result of accidental pregnancies.

Unmarried mothers and fathers actually continue to esteem marriage and desire to get married eventually, research shows. But they no longer think it's important to be married before having children.

Have a child first, then look around for a suitable spouse. That's the prevailing practice.

Women who follow this recipe usually end up in chronic poverty, on welfare, and trapped in a series of fractious cohabitations with uncommitted men.

The idea of "child first, marriage later" rarely leads to successful marriages and families. Rather, it's a roadmap to misery for men, women and children - especially children. Unfortunately, society never communicates this harsh fact to young women at risk of having children outside marriage.

Given the effectiveness of marriage in reducing poverty, one would think the nation's welfare industry would encourage marriage. Guess again.

Unfortunately, encouraging marriage is a major felony in the creed of political correctness. Despite the transparent linkages among poverty, social problems and disintegration of the family, most political elites remain silent on the issue. The welfare system, meanwhile, continues to penalize marriage.

This is a tragedy. To reduce poverty, we must begin to restore marriage in low-income communities.

Step one: Inform young men and women of the importance of marriage in reducing poverty and improving children's well-being. Step two: Provide interested low-income couples with practical information on strengthening relationships. Step three: Reduce the marriage penalties in welfare programs.

Our current system is a catastrophe. The poor deserve a new approach, one that offers real hope for the future.

Robert Rector, an authority on poverty and welfare in America, is a senior research fellow in domestic policy at The Heritage Foundation.